Modifier And Modified Conjugated Diene-Based Polymer Including Functional Group Derived Therefrom

ABSTRACT

The present invention relates to a modifier represented by Formula 1, a modified conjugated diene-based polymer having a high modification ratio which includes a modifier-derived functional group, and a method of preparing the polymer.

TECHNICAL FIELD Cross-Reference to Related Applications

This application claims the benefit of Korean Patent Application Nos.10-2016-0166994, filed on Dec. 8, 2016, and 10-2017-0153284, filed onNov. 16, 2017, in the Korean Intellectual Property Office, thedisclosure of which is incorporated herein in its entirety by reference.

TECHNICAL FIELD

The present invention relates to a modifier represented by Formula 1, amodified conjugated diene-based polymer having a high modification ratiowhich includes a modifier-derived functional group, and a method ofpreparing the polymer.

BACKGROUND ART

In line with the recent demand for fuel-efficient cars, a conjugateddiene-based polymer having adjustment stability represented by wet skidresistance as well as low rolling resistance and excellent abrasionresistance and tensile properties is required as a rubber material for atire.

In order to reduce the rolling resistance of a tire, there is a methodof reducing a hysteresis loss of a vulcanized rubber, and reboundresilience at 50° C. to 80° C., Tan δ, or Goodrich heat generation isused as an evaluation index of the vulcanized rubber. That is, it isdesirable to use a rubber material having high rebound resilience at theabove temperature or low Tan δ or Goodrich heat generation.

A natural rubber, a polyisoprene rubber, or a polybutadiene rubber isknown as a rubber material having a low hysteresis loss, but theserubbers may have low wet skid resistance. Thus, recently, a conjugateddiene-based (co)polymer, such as a styrene-butadiene rubber(hereinafter, referred to as “SBR”) or a butadiene rubber (hereinafter,referred to as “BR”), is prepared by emulsion polymerization or solutionpolymerization to be used as a rubber for a tire.

In a case in which the BR or SBR is used as the rubber material for atire, the BR or SBR is typically used by being blended with a filler,such as silica or carbon black, to obtain physical properties requiredfor a tire. However, since an affinity of the Br or SBR with the filleris poor, physical properties, such as abrasion resistance, crackresistance, or processability, may rather be reduced.

Thus, as a method of increasing dispersibility of the SBR and the fillersuch as silica or carbon black, a method of modifying a polymerizationactive site of a conjugated diene-based polymer obtained by anionicpolymerization using organolithium with a functional group capable ofinteracting with the filler has been proposed. For example, a method ofmodifying a polymerization active end of a conjugated diene-basedpolymer with a tin-based compound or introducing an amino group, or amethod of modifying with an alkoxysilane derivative has been proposed.

Also, as a method of increasing dispersibility of the BR and the fillersuch as silica or carbon black, a method of modifying a living activeterminal with a specific coupling agent or modifier has been developedin a living polymer obtained by coordination polymerization using acatalyst composition which includes a lanthanide rare earth elementcompound.

However, since the BR or SBR modified by the above-described method hasa low terminal modification ratio, a physical property improvementeffect was insignificant with respect to a tire prepared by using thesame.

DISCLOSURE OF THE INVENTION Technical Problem

The present invention provides a modifier useful for polymermodification.

The present invention also provides a modified conjugated diene-basedpolymer having a high modification ratio which includes amodifier-derived functional group.

The present invention also provides a method of preparing the modifiedconjugated diene-based polymer.

Technical Solution

According to an aspect of the present invention, there is provided amodifier represented by Formula 1.

In Formula 1,

R₁, R₂, and R₅ are each independently a monovalent hydrocarbon grouphaving 1 to 20 carbon atoms which is substituted or unsubstituted withat least one substituent selected from the group consisting of an alkylgroup having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20carbon atoms, and an aryl group having 6 to 30 carbon atoms,

R₃ and R₄ are each independently a divalent hydrocarbon group having 1to 20 carbon atoms which is substituted or unsubstituted with an alkylgroup having 1 to 20 carbon atoms, and

n is an integer of 1 to 3.

According to another aspect of the present invention, there is provideda modified conjugated diene-based polymer including a functional groupderived from a modifier represented by Formula 1.

In Formula 1,

R₁, R₂, and R₅ are each independently a monovalent hydrocarbon grouphaving 1 to 20 carbon atoms which is substituted or unsubstituted withat least one substituent selected from the group consisting of an alkylgroup having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20carbon atoms, and an aryl group having 6 to 30 carbon atoms,

R₃ and R₄ are each independently a divalent hydrocarbon group having 1to 20 carbon atoms which is substituted or unsubstituted with an alkylgroup having 1 to 20 carbon atoms, and

n is an integer of 1 to 3.

According to another aspect of the present invention, there is provideda method of preparing the modified conjugated diene-based polymer whichincludes: preparing an active polymer coupled with an organometal bypolymerization of a conjugated diene-based monomer in a hydrocarbonsolvent in the presence of a catalyst composition including a lanthaniderare earth element-containing compound (step 1); and reacting the activepolymer with the modifier represented by Formula 1 (step 2).

Advantageous Effects

Since a modifier represented by Formula 1 according to the presentinvention has high anionic reactivity due to the introduction of apolymer reactive functional group, for example, an ester group, themodifier may easily react with an active site of a polymer, and thus,modification may be easily performed.

Also, a modified conjugated diene-based polymer according to the presentinvention may have excellent affinity with a filler, such as carbonblack, by including a function group derived from the modifierrepresented by Formula 1.

In addition, a method of preparing a modified conjugated diene-basedpolymer according to the present invention may easily prepare a modifiedconjugated diene-based polymer having a high modification ratio by usingthe modifier represented by Formula 1.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in more detail toallow for a clearer understanding of the present invention.

It will be understood that words or terms used in the specification andclaims shall not be interpreted as the meaning defined in commonly useddictionaries. It will be further understood that the words or termsshould be interpreted as having a meaning that is consistent with theirmeaning in the context of the relevant art and the technical idea of theinvention, based on the principle that an inventor may properly definethe meaning of the words or terms to best explain the invention.

The present invention provides a modifier useful for modification of amodified conjugated diene-based polymer.

The modifier according to an embodiment of the present invention isrepresented by Formula 1 below.

In Formula 1,

R₁, R₂, and R₅ are each independently a monovalent hydrocarbon grouphaving 1 to 20 carbon atoms which is substituted or unsubstituted withat least one substituent selected from the group consisting of an alkylgroup having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20carbon atoms, and an aryl group having 6 to 30 carbon atoms,

R₃ and R₄ are each independently a divalent hydrocarbon group having 1to 20 carbon atoms which is substituted or unsubstituted with an alkylgroup having 1 to 20 carbon atoms, and

n is an integer of 1 to 3.

Specifically, in Formula 1, R₁, R₂, and R₅ are each independently amonovalent hydrocarbon group having 1 to 20 carbon atoms which issubstituted or unsubstituted with a substituent, wherein, in a case inwhich R₁, R₂, and R₅ are monovalent hydrocarbon groups having 1 to 20carbon atoms which are substituted with a substituent, R₁, R₂, and R₅may each independently be an alkyl group having 1 to 20 carbon atomswhich is substituted with at least one substituent selected from thegroup consisting of an alkyl group having 1 to 20 carbon atoms, acycloalkyl group having 3 to 20 carbon atoms, and an aryl group having 6to 20 carbon atoms.

Specifically, R₁, R₂, and R₅ may each independently be an alkyl grouphaving 1 to 10 carbon atoms which is substituted with at least onesubstituent selected from the group consisting of an alkyl group having1 to 10 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, andan aryl group having 6 to 12 carbon atoms, and, for example, may eachindependently an alkyl group having 1 to 10 carbon atoms which issubstituted with an alkyl group having 1 to 10 carbon atoms.

Also, R₁, R₂, and R₅ may be unsubstituted alkyl groups having 1 to 20carbon atoms, particularly alkyl groups having to 10 carbon atoms, andmore particularly alkyl groups having 1 to 6 carbon atoms.

Furthermore, in Formula 1, R₃ and R₄ are each independently a divalenthydrocarbon group having 1 to 20 carbon atoms which is substituted orunsubstituted with an alkyl group, wherein, in a case in which R₃ and R₄are divalent hydrocarbon groups having 1 to 20 carbon atoms which aresubstituted with an alkyl group, R₃ and R₄ may each independently be analkylene group having 1 to 10 carbon atoms which is substituted with analkyl group having 1 to 10 carbon atoms, and, specifically, R₃ and R₄may each independently be an alkylene group having 1 to 6 carbon atomswhich is substituted with an alkyl group having 1 to 6 carbon atoms.

Also, in Formula 1, in a case in which R₃ and R₄ are each independentlyan unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms,R₃ and R₄ may each independently be an alkylene group having 1 to 10carbon atoms, R₃ and R₄ may particularly each independently be analkylene group having 1 to 6 carbon atoms, and R₃ and R₄ may moreparticularly be an alkylene group having 1 to 3 carbon atoms at the sametime.

Specifically, in the modifier of Formula 1, R₁, R₂, and R₅ may eachindependently be an alkyl group having 1 to 10 carbon atoms which issubstituted or unsubstituted with an alkyl group having 1 to 10 carbonatoms, R₃ and R₄ may each independently be an alkylene group having 1 to6 carbon atoms, and n may be an integer of 1 to 3, and, for example, inFormula 1, R₁, R₂, and R₅ may each independently be an alkyl grouphaving 1 to 10 carbon atoms, R₃ and R₄ may each independently be analkylene group having 1 to 6 carbon atoms, and n may be an integer of 1to 3.

Specifically, the modifier represented by Formula 1 may be representedby Formulae 1-1 to 1-5.

The modifier may have a solubility in 100 g of a non-polar solvent, forexample, n-hexane, of 10 g or more at 25° C. and 1 atmosphere. Herein,the solubility of the modifier denotes a degree to which the modifier isclearly dissolved without a turbidity phenomenon during visualobservation. Thus, the modifier according to the embodiment of thepresent invention may improve a modification ratio of a polymer by beingused as a modifier for the polymer.

Also, the modifier represented by Formula 1 according to the presentinvention may easily modify a conjugated diene-based polymer at a highmodification ratio by including a reactive functional group for theconjugated diene-based polymer, a filler affinity functional group, anda solvent affinity functional group, and may improve abrasionresistance, low fuel consumption property, and processability of arubber composition including the modifier and a molded article, such asa tire, prepared therefrom. Specifically, the modifier of Formula 1 mayinclude an ester group, as a reactive functional group for the polymer,and an amine group in the molecule as described above, and, since thereactive functional group may modify the conjugated diene-based polymerat a high modification ratio by having a high reactivity with an activesite of the conjugated diene-based polymer, the functional groupsubstituted with the modifier may be introduced into the conjugateddiene-based polymer in a high yield. Also, the amine group may furtherimprove affinity with a filler, particularly, carbon black, whilereacting with a conjugated diene-based polymer end to be converted to aprimary or secondary amino group.

Furthermore, the present invention provides a modified conjugateddiene-based polymer including a functional group derived from a modifierrepresented by Formula 1 below.

In Formula 1,

R₁, R₂, and R₅ are each independently a monovalent hydrocarbon grouphaving 1 to 20 carbon atoms which is substituted or unsubstituted withat least one substituent selected from the group consisting of an alkylgroup having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20carbon atoms, and an aryl group having 6 to 30 carbon atoms,

R₃ and R₄ are each independently a divalent hydrocarbon group having 1to 20 carbon atoms which is substituted or unsubstituted with an alkylgroup having 1 to 20 carbon atoms, and

n is an integer of 1 to 3.

The modified conjugated diene-based polymer according to an embodimentof the present invention may be prepared by reacting an active polymerwith the modifier represented by Formula 1 through a preparation methodto be described later, and physical properties of the modifiedconjugated diene-based polymer may be improved by including thefunctional group derived from the modifier represented by Formula 1.

Specifically, the modifier represented by Formula 1 may be the same asdescribed above.

Specifically, the modified conjugated diene-based polymer may include afiller affinity functional group and a solvent affinity functional groupby including the functional group derived from the modifier representedby Formula 1, and thus, abrasion resistance, low fuel consumptionproperty, and processability of a rubber composition including themodified conjugated diene-based polymer and a molded article, such as atire, prepared therefrom may be improved.

The modified conjugated diene-based polymer may have a number-averagemolecular weight (Mn) of 100,000 g/mol to 500,000 g/mol, for example,100,000 g/mol to 400,000 g/mol.

Also, the modified conjugated diene-based polymer may have aweight-average molecular weight (Mw) of 300,000 g/mol to 1,000,000g/mol, for example, 400,000 g/mol to 1,000,000 g/mol.

Furthermore, the modified conjugated diene-based polymer may have anarrow molecular weight distribution (Mw/Mn), and, specifically, themolecular weight distribution of the modified conjugated diene-basedpolymer may be in a range of 2.0 to 3.0. Since the modified conjugateddiene-based polymer according to the embodiment of the present inventionhas a narrow molecular weight distribution as described above, themodified conjugated diene-based polymer according to the embodiment ofthe present invention may improve tensile properties and viscoelasticityof a rubber composition and a rubber sample in which the modifiedconjugated diene-based polymer is used.

In addition, in consideration of an improvement in balance betweenmechanical properties, an elastic modulus, and processability of therubber composition when the modified conjugated diene-based polymeraccording to the embodiment of the present invention is used in therubber composition, the weight-average molecular weight and thenumber-average molecular weight may satisfy the above-described rangesat the same time while the modified conjugated diene-based polymer hasthe above-described molecular weight distribution range.

Specifically, the modified conjugated diene-based polymer may have amolecular weight distribution of 3.0 or less, a weight-average molecularweight of 300,000 g/mol to 1,000,000 g/mol, and a number-averagemolecular weight of 100,000 g/mol to 500,000 g/mol, and, for example,may have a molecular weight distribution of 2.8 or less, aweight-average molecular weight of 400,000 g/mol to 1,000,000 g/mol, anda number-average molecular weight of 100,000 g/mol to 400,000 g/mol.

Herein, each of the weight-average molecular weight and thenumber-average molecular weight is a polystyrene-equivalent molecularweight analyzed by gel permeation chromatography (GPC), and themolecular weight distribution (Mw/Mn) is also known as polydispersity,wherein it was calculated as a ratio (Mw/Mn) of the weight-averagemolecular weight (Mw) to the number-average molecular weight (Mn).

Also, the modified conjugated diene-based polymer according to theembodiment of the present invention may be a polymer having highlinearity in which a value of −S/R (stress/relaxation) at 100° C. is 0.7or more. In this case, the −S/R denotes a change in stress in responseto the same amount of strain generated in a material, wherein it is anindex indicating linearity of a polymer. Normally, the linearity of thepolymer is low as the −S/R value is reduced, and rolling resistance orrotation resistance when the polymer is used in the rubber compositionis increased as the linearity is reduced. Furthermore, branching degreeand molecular weight distribution of the polymer may be estimated fromthe −S/R value, and the higher the −S/R value is, the higher thebranching degree is and the wider the molecular weight distribution is.As a result, processability of the polymer is excellent, but mechanicalproperties are low.

Since the modified conjugated diene-based polymer according to theembodiment of the present invention has a high −S/R value of 0.7 or moreat 100° C. as described above, resistance characteristics and fuelconsumption property may be excellent when used in the rubbercomposition. Specifically, the −S/R value of the modified conjugateddiene-based polymer may be in a range of 0.7 to 1.0.

Herein, the −S/R value was measured with a large rotor at a rotor speedof 2±0.02 rpm at 100° C. using a Mooney viscometer, for example, MV2000Eby Monsanto Company. Specifically, after the polymer was left standingfor 30 minutes or more at room temperature (23±3° C.), 27±3 g of thepolymer was taken and filled into a die cavity, Mooney viscosity wasmeasured while applying a torque by operating a platen, and the −S/Rvalue was obtained by measuring a slope of change in the Mooneyviscosity obtained while the torque was released.

Also, specifically, the modified conjugated diene-based polymer may havea cis-1,4 bond content of a conjugated diene portion, which is measuredby Fourier transform infrared spectroscopy (FT-IR), of 95% or more, forexample, 96% or more. Thus, abrasion resistance, crack resistance, andozone resistance of the rubber composition may be improved when used inthe rubber composition.

Furthermore, the modified conjugated diene-based polymer may have avinyl content of the conjugated diene portion, which is measured byFourier transform infrared spectroscopy, of 5% or less, for example, 2%or less. In a case in which the vinyl content in the polymer is greaterthan 5%, the abrasion resistance, crack resistance, and ozone resistanceof the rubber composition including the same may be deteriorated.

Herein, the cis-1,4 bond content and vinyl content in the polymer aremeasured by the Fourier transform infrared spectroscopy (FT-IR) inwhich, after measuring a FT-IR transmittance spectrum of a carbondisulfide solution of the conjugated diene-based polymer which isprepared at a concentration of 5 mg/mL by using disulfide carbon of thesame cell as a blank, each content was obtained by using a maximum peakvalue (a, base line) near 1,130 cm⁻¹ of the measurement spectrum, aminimum value (b) near 967 cm⁻¹ which indicates a trans-1,4 bond, aminimum value (c) near 911 cm⁻¹ which indicates a vinyl bond, and aminimum value (d) near 736 cm⁻¹ which indicates a cis-1,4 bond.

In addition, the present invention provides a method of preparing amodified conjugated diene-based polymer including a functional groupderived from the modifier represented by Formula 1.

The preparation method according to an embodiment of the presentinvention includes the steps of: preparing an active polymer bypolymerization of a conjugated diene-based monomer in a hydrocarbonsolvent in the presence of a catalyst composition including a lanthaniderare earth element-containing compound (step 1); and reacting the activepolymer with a modifier represented by Formula 1 (step 2).

In Formula 1,

R₁, R₂, and R₅ are each independently a monovalent hydrocarbon grouphaving 1 to 20 carbon atoms which is substituted or unsubstituted withat least one substituent selected from the group consisting of an alkylgroup having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20carbon atoms, and an aryl group having 6 to 30 carbon atoms,

R₃ and R₄ are each independently a divalent hydrocarbon group having 1to 20 carbon atoms which is substituted or unsubstituted with an alkylgroup having 1 to 20 carbon atoms, and

n is an integer of 1 to 3.

Specifically, the modifier represented by Formula 1 may be the same asdescribed above.

Step 1 is a step for preparing an active polymer coupled with anorganometal by using a catalyst composition including a lanthanide rareearth element-containing compound, wherein step 1 may be performed bypolymerization of a conjugated diene-based monomer in a hydrocarbonsolvent in the presence of the catalyst composition.

The conjugated diene-based monomer is not particularly limited, but, forexample, may be at least one selected from the group consisting of1,3-butadiene, 2,3-dimethyl-1,3-butadiene, piperylene,3-butyl-1,3-octadiene, isoprene, and 2-phenyl-1,3-butadiene.

The hydrocarbon solvent is not particularly limited, but, for example,may be at least one selected from the group consisting of n-pentane,n-hexane, n-heptane, isooctane, cyclohexane, toluene, benzene, andxylene.

The catalyst composition may be used in an amount such that thelanthanide rare earth element-containing compound is included in anamount of 0.1 mmol to 0.5 mmol based on total 100 g of the conjugateddiene-based monomer, and may specifically be used in an amount such thatthe lanthanide rare earth element-containing compound is included in anamount of 0.1 mmol to 0.4 mmol, for example, 0.1 mmol to 0.25 mmol,based on total 100 g of the conjugated diene-based monomer.

The lanthanide rare earth element-containing compound is notparticularly limited, but, for example, may be at least one compound ofrare earth metals with an atomic number of 57 to 71, such as lanthanum,neodymium, cerium, gadolinium, or praseodymium, and may specifically bea compound including at least one selected from the group consisting ofneodymium, lanthanum, and gadolinium.

Also, the lanthanide rare earth element-containing compound may includecarboxylates containing the above-described rare earth element (e.g.,neodymium acetate, neodymium acrylate, neodymium methacrylate, neodymiumgluconate, neodymium citrate, neodymium fumarate, neodymium lactate,neodymium maleate, neodymium oxalate, neodymium 2-ethylhexanoate, orneodymium neodecanoate); organophosphates containing the above-describedrare earth element (e.g., neodymium dibutyl phosphate, neodymiumdipentyl phosphate, neodymium dihexyl phosphate, neodymium diheptylphosphate, neodymium dioctyl phosphate, neodymium bis(1-methylheptyl)phosphate, neodymium bis(2-ethylhexyl) phosphate, or neodymium didecylphosphate); organophosphonates containing the above-described rare earthelement (e.g., neodymium butyl phosphonate, neodymium pentylphosphonate, neodymium hexyl phosphonate, neodymium heptyl phosphonate,neodymium octyl phosphonate, neodymium (1-methylheptyl) phosphonate,neodymium (2-ethylhexyl) phosphonate, neodymium decyl phosphonate,neodymium dodecyl phosphonate, or neodymium octadecyl phosphonate);organophosphinates containing the above-described rare earth element(e.g., neodymium butylphosphinate, neodymium pentylphosphinate,neodymium hexylphosphinate, neodymium heptylphosphinate, neodymiumoctylphosphinate, neodymium (1-methylheptyl)phosphinate, or neodymium(2-ethylhexyl)phosphinate); carbamates containing the above-describedrare earth element (e.g., neodymium dimethylcarbamate, neodymiumdiethylcarbamate, neodymium diisopropylcarbamate, neodymiumdibutylcarbamate, or neodymium dibenzylcarbamate); dithiocarbamatescontaining the above-described rare earth element (e.g., neodymiumdimethyldithiocarbamate, neodymium diethyldithiocarbamate, neodymiumdiisopropyldithiocarbamate, or neodymium dibutyldithiocarbamate);xanthates containing the above-described rare earth element (e.g.,neodymium methylxanthate, neodymium ethylxanthate, neodymiumisopropylxanthate, neodymium butylxanthate, or neodymiumbenzylxanthate); β-diketonates containing the above-described rare earthelement (e.g., neodymium acetylacetonate, neodymiumtrifluoroacetylacetonate, neodymium hexafluoroacetylacetonate, orneodymium benzoylacetonate); alkoxides or aryloxides containing theabove-described rare earth element (e.g., neodymium methoxide, neodymiumethoxide, neodymium isopropoxide, neodymium phenoxide, or neodymiumnonylphenoxide); halides or pseudo-halides containing theabove-described rare earth element (e.g., neodymium fluoride, neodymiumchloride, neodymium bromide, neodymium iodide, neodymium cyanide,neodymium cyanate, neodymium thiocyanate, or neodymium azide);oxyhalides containing the above-described rare earth element (e.g.,neodymium oxyfluoride, neodymium oxychloride, or neodymium oxybromide);or organolanthanide rare earth element-containing compounds including atleast one rare earth element-carbon bond (e.g., Cp₃Ln, Cp₂LnR, Cp₂LnCl,CpLnCl₂, CpLn (cyclooctatetraene), (C₅Me₅)₂LnR, LnR₃, Ln(allyl)₃, orLn(allyl)₂Cl, where Ln represents a rare earth metal element, and Rrepresents hydrocarbyl group), and may include any one thereof ormixture of two or more thereof.

Specifically, the lanthanide rare earth element-containing compound mayinclude a neodymium-based compound represented by Formula 3 below.

In Formula 3, R_(a) to R_(c) may each independently be hydrogen or analkyl group having 1 to 12 carbon atoms, but all of R_(a) to R_(c) arenot hydrogen at the same time.

As a specific example, the neodymium-based compound may be at least oneselected from the group consisting of Nd(neodecanoate)₃,Nd(2-ethylhexanoate)₃, Nd(2,2-diethyl decanoate)₃, Nd(2,2-dipropyldecanoate)₃, Nd(2,2-dibutyl decanoate)₃, Nd(2,2-dihexyl decanoate)₃,Nd(2,2-dioctyl decanoate)₃, Nd(2-ethyl-2-propyl decanoate)₃,Nd(2-ethyl-2-butyl decanoate)₃, Nd(2-ethyl-2-hexyl decanoate)₃,Nd(2-propyl-2-butyl decanoate)₃, Nd(2-propyl-2-hexyl decanoate)₃,Nd(2-propyl-2-isopropyl decanoate)₃, Nd(2-butyl-2-hexyl decanoate)₃,Nd(2-hexyl-2-octyl decanoate)₃, Nd(2-t-butyl decanoate)₃, Nd(2,2-diethyloctanoate)₃, Nd(2,2-dipropyl octanoate)₃, Nd(2,2-dibutyl octanoate)₃,Nd(2,2-dihexyl octanoate)₃, Nd(2-ethyl-2-propyl octanoate)₃,Nd(2-ethyl-2-hexyl octanoate)₃, Nd(2,2-diethyl nonanoate)₃,Nd(2,2-dipropyl nonanoate)₃, Nd(2,2-dibutyl nonanoate)₃, Nd(2,2-dihexylnonanoate)₃, Nd(2-ethyl-2-propyl nonanoate)₃, and Nd(2-ethyl-2-hexylnonanoate)₃.

As another example, in consideration of excellent solubility in thepolymerization solvent without a concern for oligomerization, a rate ofconversion to a catalytically active species, and the resultingexcellent catalytic activity improvement effect, the lanthanide rareearth element-containing compound may specifically be a neodymium-basedcompound in which, in Formula 3, R_(a) is a linear or branched alkylgroup having 4 to 12 carbon atoms, and R_(b) and R_(c) are eachindependently hydrogen or an alkyl group having 2 to 8 carbon atoms, butR_(b) and R_(c) are not hydrogen at the same time.

As a specific example, in Formula 3, R_(a) may be a linear or branchedalkyl group having 6 to 8 carbon atoms, and R_(b) and R_(c) may eachindependently be hydrogen or an alkyl group having 2 to 6 carbon atoms,wherein R_(b) and R_(c) may not be hydrogen at the same time, specificexamples of the neodymium-based compound may be at least one selectedfrom the group consisting of Nd (2,2-diethyl decanoate)₃,Nd(2,2-dipropyl decanoate)₃, Nd(2,2-dibutyl decanoate)₃, Nd(2,2-dihexyldecanoate)₃, Nd(2,2-dioctyl decanoate)₃, Nd(2-ethyl-2-propyldecanoate)₃, Nd (2-ethyl-2-butyl decanoate)₃, Nd (2-ethyl-2-hexyldecanoate)₃, Nd (2-propyl-2-butyl decanoate)₃, Nd(2-propyl-2-hexyldecanoate)₃, Nd(2-propyl-2-isopropyl decanoate)₃, Nd(2-butyl-2-hexyldecanoate)₃, Nd(2-hexyl-2-octyl decanoate)₃, Nd(2-t-butyl decanoate)₃,Nd(2,2-diethyl octanoate)₃, Nd(2,2-dipropyl octanoate)₃, Nd(2,2-dibutyloctanoate)₃, Nd (2,2-dihexyl octanoate)₃, Nd (2-ethyl-2-propyloctanoate)₃, Nd(2-ethyl-2-hexyl octanoate)₃, Nd(2,2-diethyl nonanoate)₃,Nd (2,2-dipropyl nonanoate)₃, Nd(2,2-dibutyl nonanoate)₃, Nd(2,2-dihexyl nonanoate)₃, Nd (2-ethyl-2-propyl nonanoate)₃, andNd(2-ethyl-2-hexyl nonanoate)₃, and, among them, the neodymium-basedcompound may be at least one selected from the group consisting ofNd(2,2-diethyl decanoate)₃, Nd(2,2-dipropyl decanoate)₃, Nd(2,2-dibutyldecanoate)₃, Nd(2,2-dihexyl decanoate)₃, and Nd(2,2-dioctyl decanoate)₃.

Specifically, in Formula 3, R_(d) may be a linear or branched alkylgroup having 6 to 8 carbon atoms, and R_(b) and R_(c) may eachindependently be an alkyl group having 2 to 6 carbon atoms.

As described above, since the neodymium-based compound represented byFormula 3 includes a carboxylate ligand including alkyl groups ofvarious lengths having 2 or more carbon atoms as a substituent at an α(alpha) position, coagulation of the compound may be blocked by inducingsteric changes around the neodymium center metal, and accordingly,oligomerization may be suppressed. Also, with respect to theneodymium-based compound, since a ratio of neodymium located in a centerportion, which has high solubility in the polymerization solvent and hasdifficulties in conversion to the catalytically active species, isreduced, the rate of conversion to the catalytically active species ishigh.

Furthermore, the lanthanide rare earth element-containing compoundaccording to an embodiment of the present invention may have asolubility of about 4 g or more per 6 g of a non-polar solvent at roomtemperature (25° C.)

In the present invention, the solubility of the neodymium-based compounddenotes a degree to which the neodymium-based compound is clearlydissolved without a turbidity phenomenon, wherein since theneodymium-based compound has high solubility as described above,excellent catalytic activity may be achieved.

Also, the lanthanide rare earth element-containing compound according tothe embodiment of the present invention may be used in the form of areactant with a Lewis base. The reactant may improve the solubility ofthe lanthanide rare earth element-containing compound in the solvent andmay be stored in stable state for a long period of time by the Lewisbase. The Lewis base, for example, may be used in ratio of 30 mol orless or 1 mole to 10 mol per 1 mol of the rare earth element. Examplesof the Lewis base may be acetylacetone, tetrahydrofuran, pyridine,N,N′-dimethylformamide, thiophene, diphenyl ether, triethylamine, anorganic phosphorus compound, or a monohydric or dihydric alcohol.

The catalyst composition may further include at least one of (a)alkylating agent, (b) halide, and (c) conjugated diene-based monomer, inaddition to the lanthanide rare earth element-containing compound.

Hereinafter, (a) alkylating agent, (b) halide, and (c) conjugateddiene-based monomer will be separately described in detail.

(a) Alkylating Agent

The alkylating agent is an organometallic compound that may transfer ahydrocarbyl group to another metal, wherein it may act as a cocatalystcomposition. The alkylating agent may be used without particularlimitation as long as it is commonly used as an alkylating agent duringthe preparation of a diene-based polymer, and, for example, may be anorganometallic compound, which is soluble in the polymerization solventand contains a metal-carbon bond, such as an organoaluminum compound, anorganomagnesium compound, or an organolithium compound.

Specifically, the organoaluminum compound may include alkylaluminum suchas trimethylaluminum, triethylaluminum, tri-n-propylaluminum,triisopropylaluminum, tri-n-butylaluminum, triisobutylaluminum,tri-t-butylaluminum, tripentylaluminum, trihexylaluminum,tricyclohexylaluminum, or trioctylaluminum; dihydrocarbylaluminumhydride such as diethylaluminum hydride, di-n-propylaluminum hydride,diisopropylaluminum hydride, di-n-butylaluminum hydride,diisobutylaluminum hydride (DIBAH), di-n-octylaluminum hydride,diphenylaluminum hydride, di-p-tolylaluminum hydride, dibenzylaluminumhydride, phenylethylaluminum hydride, phenyl-n-propylaluminum hydride,phenylisopropylaluminum hydride, phenyl-n-butylaluminum hydride,phenylisobutylaluminum hydride, phenyl-n-octylaluminum hydride,p-tolylethylaluminum hydride, p-tolyl-n-propylaluminum hydride,p-tolylisopropylaluminum hydride, p-tolyl-n-butylaluminum hydride,p-tolylisobutylaluminum hydride, p-tolyl-n-octylaluminum hydride,benzylethylaluminum hydride, benzyl-n-propylaluminum hydride,benzylisopropylaluminum hydride, benzyl-n-butylaluminum hydride,benzylisobutylaluminum hydride, or benzyl-n-octylaluminum hydride; andhydrocarbylaluminum dihydride such as ethylaluminum dihydride,n-propylaluminum dihydride, isopropylaluminum dihydride, n-butylaluminumdihydride, isobutylaluminum dihydride, or n-octylaluminum dihydride. Theorganomagnesium compound may include an alkyl magnesium compound such asdiethylmagnesium, di-n-propylmagnesium, diisopropylmagnesium,dibutylmagnesium, dihexylmagnesium, diphenylmagnesium, ordibenzylmagnesium, and the organolithium compound may include an alkyllithium compound such as n-butyllithium.

Also, the organoaluminum compound may be aluminoxane.

The aluminoxane may be prepared by reacting atrihydrocarbylaluminum-based compound with water, and may specificallybe linear aluminoxane of the following Formula 4a or cyclic aluminoxaneof the following Formula 4b.

In Formulae 4a and 4b, R is a monovalent organic group bonded to analuminum atom through a carbon atom, wherein R may be a hydrocarbylgroup, and x and y may each independently be an integer of 1 or more,particularly 1 to 100, and more particularly 2 to 50.

For example, the aluminoxane may include methylaluminoxane (MAO),modified methylaluminoxane (MAO), ethylaluminoxane, n-propylaluminoxane,isopropylaluminoxane, butylaluminoxane, isobutylaluminoxane,n-pentylaluminoxane, neopentylaluminoxane, n-hexylaluminoxane,n-octylaluminoxane, 2-ethylhexylaluminoxane, cylcohexylaluminoxane,1-methylcyclopentylaluminoxane, phenylaluminoxane, or2,6-dimethylphenylaluminoxane, and any one thereof or a mixture of twoor more thereof may be used.

Furthermore, the modified methylaluminoxane may be one in which a methylgroup of methylaluminoxane is substituted with a formula group (R),specifically, a hydrocarbon group having 2 to 20 carbon atoms, whereinthe modified methylaluminoxane may specifically be a compoundrepresented by Formula 5 below.

In Formula 5, R is the same as defined above, and m and n may eachindependently be an integer of 2 or more. Also, in Formula 5, Merepresents a methyl group.

Specifically, in Formula 5, R may be an alkyl group having 2 to 20carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an alkenylgroup having 2 to 20 carbon atoms, a cycloalkenyl group having 3 to 20carbon atoms, an aryl group having 6 to 20 carbon atoms, an arylalkylgroup having to 20 carbon atoms, an alkylaryl group having 7 to 20carbon atoms, an allyl group, or an alkynyl group having 2 to 20 carbonatoms, may particularly be an alkyl group having 2 to 20 carbon atomssuch as an ethyl group, an isobutyl group, a hexyl group, or an octylgroup, and may more particularly be an isobutyl group.

Specifically, the modified methylaluminoxane may be one in which about50 mol % to 90 mol % of the methyl group of the methylaluminoxane issubstituted with the above-described hydrocarbon group. When the amountof the hydrocarbon group substituted in the modified methylaluminoxaneis within the above range, the modified methylaluminoxane may increasecatalytic activity by promoting alkylation.

The modified methylaluminoxane may be prepared by a conventional method,and may specifically be prepared by using alkylaluminum other thantrimethylaluminum. In this case, the alkylaluminum may betriisopropylaluminum, triethylaluminum, trihexylaluminum, ortrioctylaluminum, and any one thereof or a mixture of two or morethereof may be used.

Also, the catalyst composition according to an embodiment of the presentinvention may include the alkylating agent at a molar ratio of 1 to 200,particularly 1 to 100, and more particularly 3 to 20 based on 1 mol ofthe lanthanide rare earth element-containing compound. In a case inwhich the alkylating agent is included at a molar ratio of greater than200, catalytic reaction control is not easy during the preparation ofthe polymer, and an excessive amount of the alkylating agent may cause aside reaction.

(b) Halide

The halide is not particularly limited, but, for example, may includeelemental halogen, an interhalogen compound, halogenated hydrogen, anorganic halide, a non-metal halide, a metal halide, or an organic metalhalide, and any one thereof or a mixture of two or more thereof may beused. Among them, in consideration of catalytic activity enhancement andthe resulting significant improvement in reactivity, any one selectedfrom the group consisting of an organic halide, a metal halide, and anorganic metal halide, or a mixture of two or more thereof may be used asthe halide.

The elemental halogen may include fluorine, chlorine, bromine, oriodine.

Also, the interhalogen compound may include iodine monochloride, iodinemonobromide, iodine trichloride, iodine pentafluoride, iodinemonofluoride, or iodine trifluoride.

Furthermore, the halogenated hydrogen may include hydrogen fluoride,hydrogen chloride, hydrogen bromide, or hydrogen iodide.

Also, the organic halide may include t-butyl chloride (t-BuCl), t-butylbromide, allyl chloride, allyl bromide, benzyl chloride, benzyl bromide,chloro-di-phenylmethane, bromo-di-phenylmethane, triphenylmethylchloride, triphenylmethyl bromide, benzylidene chloride, benzylienebromide, methyltrichlorosilane, phenyltrichlorosilane,dimethyldichlorosilane, diphenyldichlorosilane, trimethylchlorosilane(TMSCl), benzoyl chloride, benzoyl bromide, propionyl chloride,propionyl bromide, methyl chloroformate, methyl bromoformate,iodomethane, diiodomethane, triiodomethane (also referred to as‘iodoform’), tetraiodomethane, 1-iodopropane, 2-iodopropane,1,3-diiodopropane, t-butyl iodide, 2,2-dimethyl-1-iodopropane (alsoreferred to as ‘neopentyl iodide’), allyl iodide, iodobenzene, benzyliodide, diphenylmethyl iodide, triphenylmethyl iodide, benzylideneiodide (also referred to as ‘benzal iodide’), trimethylsilyl iodide,triethylsilyl iodide, triphenylsilyl iodide, dimethyldiiodosilane,diethyldiiodosilane, diphenyldiiodosilane, methyltriiodosilane,ethyltriiodosilane, phenyltriiodosilane, benzoyl iodide, propionyliodide, or methyl iodoformate.

Furthermore, the non-metal halide may include phosphorous trichloride,phosphorous tribromide, phosphorous pentachloride, phosphorousoxychloride, phosphorous oxybromide, boron trifluoride, borontrichloride, boron tribromide, silicon tetrafluoride, silicontetrachloride (SiCl₄), silicon tetrabromide, arsenic trichloride,arsenic tribromide, selenium tetrachloride, selenium tetrabromide,tellurium tetrachloride, tellurium tetrabromide, silicon tetraiodide,arsenic triiodide, tellurium tetraiodide, boron triiodide, phosphoroustriiodide, phosphorous oxyiodide, or selenium tetraiodide.

Also, the metal halide may include tin tetrachloride, tin tetrabromide,aluminum trichloride, aluminum tribromide, antimony trichloride,antimony pentachloride, antimony tribromide, aluminum trifluoride,gallium trichloride, gallium tribromide, gallium trifluoride, indiumtrichloride, indium tribromide, indium trifluoride, titaniumtetrachloride, titanium tetrabromide, zinc dichloride, zinc dibromide,zinc difluoride, aluminum triiodide, gallium triiodide, indiumtriiodide, titanium tetraiodide, zinc diiodide, germanium tetraiodide,tin tetraiodide, tin diiodide, antimony triiodide, or magnesiumdiiodide.

Furthermore, the organic metal halide may include dimethylaluminumchloride, diethylaluminum chloride, dimethylaluminum bromide,diethylaluminum bromide, dimethylaluminum fluoride, diethylaluminumfluoride, methylaluminum dichloride, ethylaluminum dichloride,methylaluminum dibromide, ethylaluminum dibromide, methylaluminumdifluoride, ethylaluminum difluoride, methylaluminum sesquichloride,ethylaluminum sesquichloride (EASC), isobutylaluminum sesquichloride,methylmagnesium chloride, methylmagnesium bromide, ethylmagnesiumchloride, ethylmagnesium bromide, n-butylmagnesium chloride,n-butylmagnesium bromide, phenylmagnesium chloride, phenylmagnesiumbromide, benzylmagnesium chloride, trimethyltin chloride, trimethyltinbromide, triethyltin chloride, triethyltin bromide, di-t-butyltindichloride, di-t-butyltin dibromide, di-n-butyltin dichloride,di-n-butyltin dibromide, tri-n-butyltin chloride, tri-n-butyltinbromide, methylmagnesium iodide, dimethylaluminum iodide,diethylaluminum iodide, di-n-butylaluminum iodide, diisobutylaluminumiodide, di-n-octylaluminum iodide, methylaluminum diiodide,ethylaluminum diiodide, n-butylaluminum diiodide, isobutylaluminumdiiodide, methylaluminum sesquiiodide, ethylaluminum sesquiiodide,isobutylaluminum sesquiiodide, ethylmagnesium iodide, n-butylmagnesiumiodide, isobutylmagnesium iodide, phenylmagnesium iodide,benzylmagnesium iodide, trimethyltin iodide, triethyltin iodide,tri-n-butyltin iodide, di-n-butyltin diiodide, or di-t-butyl tindiiodide.

Also, the catalyst composition according to the embodiment of thepresent invention may include the halide in an amount of 1 mol to 20mol, particularly 1 mol to 5 mol, and more particularly 2 mol to 3 molbased on 1 mol of the lanthanide rare earth element-containing compound.In a case in which the halide is included in an amount of greater thanmol, catalytic reaction control is not easy and an excessive amount ofthe halide may cause a side reaction.

Furthermore, the catalyst composition for preparing a conjugated dienepolymer according to the embodiment of the present invention may includea non-coordinating anion-containing compound or a non-coordinating anionprecursor compound instead of the halide or with the halide.

Specifically, in the compound containing a non-coordinating anion, thenon-coordinating anion is a sterically bulky anion that does not form acoordinate bond with an active center of a catalyst system due to sterichindrance, wherein the non-coordinating anion may be a tetraarylborateanion or a fluorinated tetraarylborate anion. Also, the compoundcontaining a non-coordinating anion may include a counter cation, forexample, a carbonium cation such as a triarylcarbonium cation; anammonium cation, such as N,N-dialkyl anilinium cation, or a phosphoniumcation, in addition to the above-described non-coordinating anion. Forexample, the compound containing a non-coordinating anion may includetriphenylcarbonium tetrakis(pentafluorophenyl)borate,N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate,triphenylcarbonium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, orN,N-dimethylanilinium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate.

Also, the non-coordinating anion precursor, as a compound capable offorming a non-coordinating anion under the reaction conditions, mayinclude a triaryl boron compound (BE₃, where E is a strongelectron-withdrawing aryl group such as a pentafluorophenyl group or3,5-bis(trifluoromethyl)phenyl group).

(c) Conjugated Diene-Based Monomer

Also, the catalyst composition may further include a conjugateddiene-based monomer, and, since the catalyst composition is used in theform of a performing catalyst composition in which a portion of theconjugated diene-based monomer used in the polymerization reaction ispre-polymerized by being premixed with the catalyst composition forpolymerization, catalyst composition activity may not only be improved,but a conjugated diene-based polymer thus prepared may be stabilized.

In the present invention, the expression “preforming” may denote that,in a case in which a catalyst composition including a lanthanide rareearth element-containing compound, an alkylating agent, and a halide,that is, a catalyst system includes diisobutylaluminum hydride (DIBAH),a small amount of a conjugated diene-based monomer, such as1,3-butadiene, is added to reduce the possibility of producing variouscatalytically active species, and pre-polymerization is performed in thecatalyst composition system with the addition of the 1,3-butadiene.Also, the expression “premix” may denote a state in which each compoundis uniformly mixed in the catalyst composition system without beingpolymerized.

In this case, with respect to the conjugated diene-based monomer used inthe preparation of the catalyst composition, some amount within a totalamount range of the conjugated diene-based monomer used in thepolymerization reaction may be used, and, for example, the conjugateddiene-based monomer may be used in an amount of 1 mol to 100 mol, forexample, 10 mol to 50 mol, or 20 mol to 50 mol based on 1 mol of thelanthanide rare earth element-containing compound.

The catalyst composition according to the embodiment of the presentinvention may be prepared by sequentially mixing the above-describedlanthanide rare earth element-containing compound and at least one ofthe alkylating agent, the halide, and the conjugated diene-basedmonomer, specifically, the lanthanide rare earth element-containingcompound, alkylating agent, halide, and selectively conjugateddiene-based monomer, in an organic solvent. In this case, the organicsolvent may be a non-polar solvent that is not reactive with theabove-described catalyst components. Specifically, the non-polar solventmay include linear, branched, or cyclic aliphatic hydrocarbon having 5to 20 carbon atoms such as n-pentane, n-hexane, n-heptane, n-octane,n-nonane, n-decane, isopentane, isohexane, isoheptane, isooctane,2,2-dimethylbutane, cyclopentane, cyclohexane, methylcyclopentane, ormethylcyclohexane; a mixed solvent of aliphatic hydrocarbon having 5 to20 carbon atoms such as petroleum ether or petroleum spirits, orkerosene; or an aromatic hydrocarbon-based solvent such as benzene,toluene, ethylbenzene, and xylene, and any one thereof or a mixture oftwo or more thereof may be used. The non-polar solvent may morespecifically include the above-described linear, branched, or cyclicaliphatic hydrocarbon having 5 to 20 carbon atoms or the above-describedmixed solvent of aliphatic hydrocarbon, and, for example, may includen-hexane, cyclohexane, or a mixture thereof.

Also, the organic solvent may be appropriately selected depending on atype of the constituent material constituting the catalyst composition,particularly, the alkylating agent.

Specifically, since alkylaluminoxane, such as methylaluminoxane (MAO) orethylaluminoxane, as the alkylating agent, is not easily dissolved in analiphatic hydrocarbon-based solvent, an aromatic hydrocarbon-basedsolvent may be appropriately used.

Furthermore, in a case in which modified methylaluminoxane is used asthe alkylating agent, an aliphatic hydrocarbon-based solvent may beappropriately used. In this case, since a single solvent system may berealized with an aliphatic hydrocarbon-based solvent, such as hexane,mainly used as a polymerization solvent, it may be more advantageous tothe polymerization reaction. Also, the aliphatic hydrocarbon-basedsolvent may promote catalytic activity, and may further improvereactivity by the catalytic activity.

The organic solvent may be used in an amount of 20 mol to 20,000 mol,for example, 100 mol to 1,000 mol, based on 1 mol of the lanthanide rareearth element-containing compound.

The polymerization of step 1 may be performed by coordination anionicpolymerization or radical polymerization, may specifically be bulkpolymerization, solution polymerization, suspension polymerization, oremulsion polymerization, and, for example, may be solutionpolymerization.

Also, the polymerization may be performed by any method of batch andcontinuous methods. Specifically, the polymerization of step 1 may beperformed by adding the conjugated diene-based monomer to the catalystcomposition and performing a reaction in the organic solvent.

Herein, the organic solvent may be further added in addition to theamount of the organic solvent which may be used in the preparation ofthe catalyst composition, and specific types thereof may be the same asdescribed above. Also, when the organic solvent is used, a concentrationof the monomer may be in a range of 3 wt % to 80 wt %, or 10 wt % to 30wt %.

Also, during the polymerization, an additive, for example, a reactionterminating agent for the completion of the polymerization reaction,such as polyoxyethylene glycol phosphate; or an antioxidant, such as2,6-di-t-butylparacresol, may be further used. In addition, an additivethat usually facilitates solution polymerization, specifically, anadditive, such as a chelating agent, a dispersant, a pH adjuster, adeoxidizer, or an oxygen scavenger, may be further selectively used.

Furthermore, the polymerization may be temperature rise polymerization,isothermal polymerization, or constant temperature polymerization(adiabatic polymerization).

Herein, the constant temperature polymerization denotes a polymerizationmethod including a step of performing polymerization not by randomlyapplying heat but with its own reaction heat after the organometalliccompound is added, the temperature rise polymerization denotes apolymerization method in which the temperature is increased by randomlyapplying heat after the organometallic compound is added, and theisothermal polymerization denotes a polymerization method in which thetemperature of the polymer is constantly maintained by taking away heator applying heat after the organometallic compound is added.

The polymerization may be performed in a temperature range of −20° C. to200° C., particularly in a temperature range of 20° C. to 150° C., andmore particularly in a temperature range of 10° C. to 120° C. for 15minutes to 3 hours. In a case in which the temperature during thepolymerization is greater than 200° C., it is difficult to sufficientlycontrol the polymerization reaction and the cis-1,4 bond content of theformed diene-based polymer may be decreased, and, in a case in which thetemperature is less than −20° C., polymerization rate and efficiency maybe reduced.

Step 2 is a step of reacting the active polymer with the modifierrepresented by Formula 1, in order to prepare a conjugated diene-basedpolymer.

The modifier represented by Formula 1 may be the same as describedabove, and at least one type thereof may be mixed and used in thereaction.

The modifier represented by Formula 1 may be used in an amount of 0.5mol to 20 mol based on 1 mol of the lanthanide rare earthelement-containing compound in the catalyst composition. Specifically,the modifier represented by Formula 1 may be used in an amount of 1 molto 10 mol based on 1 mol of the lanthanide rare earth element-containingcompound in the catalyst composition. Since the optimal modificationreaction may be performed when the modifier is used in an amount thatsatisfies the above range, a conjugated diene-based polymer having ahigh modification ratio may be obtained.

The reaction of step 2 is a modification reaction for the introductionof a functional group into the polymer, wherein the reaction may beperformed in a temperature range of 0° C. to 90° C. for 1 minute to 5hours.

Also, the method of preparing a modified conjugated diene-based polymeraccording to the embodiment of the present invention may be performed bya batch polymerization method or a continuous polymerization methodincluding one or more reactors.

After the completion of the above-described modification reaction, thepolymerization reaction may be stopped by adding an isopropanol solutionof 2,6-di-t-butyl-p-cresol (BHT) to a polymerization reaction system.Thereafter, a modified conjugated diene-based polymer may be obtainedthrough a desolvation treatment, such as steam stripping in which apartial pressure of the solvent is reduced by supplying water vapor, ora vacuum drying treatment. Also, in addition to the above-describedmodified conjugated diene-based polymer, an unmodified active polymermay be included in a reaction product obtained as a result of theabove-described modification reaction.

The preparation method according to the embodiment of the presentinvention may further include at least one step of recovering solventand unreacted monomer and drying, if necessary, after step 2.

Furthermore, the present invention provides a rubber compositionincluding the above modified conjugated diene-based polymer and a moldedarticle prepared from the rubber composition.

The rubber composition according to an embodiment of the presentinvention may include the modified conjugated diene-based polymer in anamount of 0.1 wt % or more to 100 wt % or less, particularly 10 wt % to100 wt %, and more particularly 20 wt % to 90 wt %. In a case in whichthe amount of the modified conjugated diene-based polymer is less than0.1 wt %, an effect of improving abrasion resistance and crackresistance of a molded article prepared by using the rubber composition,for example, a tire, may be insignificant.

Also, the rubber composition may further include other rubbercomponents, if necessary, in addition to the modified conjugateddiene-based polymer, and, in this case, the rubber component may beincluded in an amount of 90 wt % or less based on a total weight of therubber composition. Specifically, the rubber component may be includedin an amount of 1 part by weight to 900 parts by weight based on 100parts by weight of the modified conjugated diene-based polymer.

The rubber component may be a natural rubber or a synthetic rubber, and,for example, the rubber component may be a natural rubber (NR) includingcis-1,4-polyisoprene; a modified natural rubber, such as an epoxidizednatural rubber (ENR), a deproteinized natural rubber (DPNR), and ahydrogenated natural rubber, in which the general natural rubber ismodified or purified; and a synthetic rubber such as a styrene-butadienerubber (SBR), polybutadiene (BR), polyisoprene (IR), a butyl rubber(IIR), an ethylene-propylene copolymer, polyisobutylene-co-isoprene,neoprene, poly(ethylene-co-propylene), poly(styrene-co-butadiene),poly(styrene-co-isoprene), poly(styrene-co-isoprene-co-butadiene),poly(isoprene-co-butadiene), poly(ethylene-co-propylene-co-diene), apolysulfide rubber, an acrylic rubber, an urethane rubber, a siliconrubber, an epichlorohydrin rubber, a butyl rubber, and a halogenatedbutyl rubber. Any one thereof or a mixture of two or more thereof may beused.

Furthermore, the rubber composition may include 0.1 part by weight to150 parts by weight of a filler based on 100 parts by weight of themodified conjugated diene-based polymer, and the filler may include asilica-based filler, a carbon black-based filler, or a combinationthereof. Specifically, the filler may be carbon black.

The carbon black-based filler is not particularly limited, but, forexample, may have a nitrogen surface area per gram (N₂SA, measuredaccording to JIS K 6217-2:2001) of 20 m²/g to 250 m²/g. Also, the carbonblack may have a dibutyl phthalate (DBP) oil absorption of 80 cc/100 gto 200 cc/100 g. If the nitrogen surface area per gram of the carbonblack is greater than 250 m²/g, processability of the rubber compositionmay be reduced, and, if the nitrogen surface area per gram of the carbonblack is less than 20 m²/g, reinforcement by carbon black may beinsignificant. Furthermore, if the DBP oil absorption of the carbonblack is greater than 200 cc/100 g, the processability of the rubbercomposition may be reduced, and, if the DBP oil absorption of the carbonblack is less than 80 cc/100 g, the reinforcement by carbon black may beinsignificant.

Also, the silica-based filler is not particularly limited, but, forexample, may include wet silica (hydrous silicic acid), dry silica(anhydrous silicic acid), calcium silicate, aluminum silicate, orcolloidal silica.

Specifically, the silica-based filler may be wet silica in which aneffect of improving both fracture characteristics and wet grip is themost significant. Furthermore, the silica may have a nitrogen surfacearea per gram (N₂SA) of 120 m²/g to 180 m²/g, and acetyltrimethylammonium bromide (CTAB) surface area per gram of 100 m²/gto 200 m²/g. If the nitrogen surface area per gram of the silica is lessthan 120 m²/g, reinforcement by silica may be insignificant, and, if thenitrogen surface area per gram of the silica is greater than 180 m²/g,the processability of the rubber composition may be reduced. Also, ifthe CTAB surface area per gram of the silica is less than 100 m²/g, thereinforcement by silica, as the filler, may be insignificant, and, ifthe CTAB surface area per gram of the silica is greater than 200 m²/g,the processability of the rubber composition may be reduced.

In a case in which silica is used as the filler, a silane coupling agentmay be used together for the improvement of reinforcement and low heatgeneration property.

Specific examples of the silane coupling agent may bebis(3-triethoxysilylpropyl)tetrasulfide,bis(3-triethoxysilylpropyl)trisulfide,bis(3-triethoxysilylpropyl)disulfide,bis(2-triethoxysilylethyl)tetrasulfide,bis(3-trimethoxysilylpropyl)tetrasulfide,bis(2-trimethoxysilylethyl)tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyl triethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyl triethoxysilane,3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide,3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide,2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide,3-trimethoxysilylpropyl benzothiazolyl tetrasulfide,3-triethoxysilylpropyl benzolyl tetrasulfide, 3-triethoxysilylpropylmethacrylate monosulfide, 3-trimethoxysilylpropyl methacrylatemonosulfide, bis(3-diethoxymethylsilylpropyl)tetrasulfide,3-mercaptopropyl dimethoxymethylsilane,dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, ordimethoxymethylsilylpropyl benzothiazolyl tetrasulfide, and any onethereof or a mixture of two or more thereof may be used. For example, inconsideration of the effect of improving the reinforcement, the silanecoupling agent may be bis(3-triethoxysilylpropyl)polysulfide or3-trimethoxysilylpropyl benzothiazyl tetrasulfide.

Furthermore, in the rubber composition according to the embodiment ofthe present invention, since the modified conjugated diene-basedpolymer, in which a function group having a high affinity with thesilica is introduced into the active site, is used as the rubbercomponent, a mixing amount of the silane coupling agent may be reducedin comparison to a conventional case. Specifically, the silane couplingagent may be used in an amount of 1 part by weight to 20 parts by weightbased on 100 parts by weight of the silica. In a case in which thesilane coupling agent is used within the above range, the silanecoupling agent may prevent gelation of the rubber component whilesufficiently having an effect as a coupling agent. For example, thesilane coupling agent may be used in an amount of 5 parts by weight to15 parts by weight based on 100 parts by weight of the silica.

Also, the rubber composition according to the embodiment of the presentinvention may be sulfur cross-linkable, and, accordingly, may furtherinclude a vulcanizing agent.

The vulcanizing agent may specifically be sulfur powder, and may beincluded in an amount of 0.1 part by weight to 10 parts by weight basedon 100 parts by weight of the rubber component. When the vulcanizingagent is included within the above range, elastic modulus and strengthrequired for the vulcanized rubber composition may be secured and,simultaneously, a low fuel consumption property may be obtained.

Furthermore, the rubber composition according to the embodiment of thepresent invention may further include various additives, such as avulcanization accelerator, process oil, a plasticizer, an antioxidant, ascorch inhibitor, zinc white, stearic acid, a thermosetting resin, or athermoplastic resin, used in the general rubber industry, in addition tothe above-described components.

The vulcanization accelerator is not particularly limited, but,specifically, a thiazole-based compound, such as 2-mercaptobenzothiazole(M), dibenzothiazyl disulfide (DM), andN-cyclohexylbenzothiazole-2-sulfenamide (CZ), or a guanidine-basedcompound, such as diphenylguanidine (DPG), may be used. Thevulcanization accelerator may be included in an amount of 0.1 part byweight to 5 parts by weight based on 100 parts by weight of the rubbercomponent.

Also, the process oil acts as a softener in the rubber composition,wherein the process oil may be a paraffin-based, naphthenic-based, oraromatic-based compound, and, for example, the aromatic-based compoundmay be used in consideration of tensile strength and abrasionresistance, and the naphthenic-based or paraffin-based process oil maybe used in consideration of hysteresis loss and low temperaturecharacteristics. The process oil may be included in an amount of 100parts by weight or less based on 100 parts by weight of the rubbercomponent, and, when the process oil is included in the above amount,decreases in tensile strength and low heat generation property (low fuelconsumption property) of the vulcanized rubber may be prevented.

Furthermore, specific examples of the antioxidant may beN-isopropyl-N′-phenyl-p-phenylenediamine,N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine,6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, or a high-temperaturecondensate of diphenylamine and acetone. The antioxidant may be used inan amount of 0.1 part by weight to 6 parts by weight based on 100 partsby weight of the rubber component.

The rubber composition according to the embodiment of the presentinvention may be obtained by kneading the above mixing formulation usinga kneader such as a Banbury mixer, a roll, and an internal mixer, and arubber composition having excellent abrasion resistance as well as lowheat generation property may also be obtained by a vulcanization processafter molding.

Accordingly, the rubber composition may be suitable for the preparationof each member of a tire, such as a tire's tread, an under tread, asidewall, a carcass coating rubber, a belt coating rubber, a beadfiller, a chafer, or a bead coating rubber, or various industrial rubberproducts such as an anti-vibration rubber, a belt conveyor, and a hose.

The molded article prepared by using the rubber composition may includea tire or a tire's tread.

Hereinafter, the present invention will be described in more detail,according to specific examples and experimental examples. However, thefollowing examples and experimental examples are merely presented toexemplify the present invention, and the scope of the present inventionis not limited thereto.

Preparation Example 1

After a methylene chloride solution, in which 10 g (63.2 mmol) of methylpiperazine-1-carboxylate was dissolved, was added to a 1 L round-bottomflask, a methylene chloride solution, in which 17.6 ml (126.4 mmol) oftriethylamine and 8.8 ml (69.5 mmol) of trimethylsilyl chloride weredissolved at 0° C., was sequentially added. Thereafter, a reaction wasperformed while stirring for 12 hours at room temperature, the reactionwas terminated, hexane was added to dilute the solution, and the solventwas then removed under reduced pressure. Thereafter, a washing processwas repeated three times using hexane to obtain a modifier representedby the following Formula 1-1. ¹H nuclear magnetic resonancespectroscopic data of the obtained modifier represented by Formula 1-1are as follows.

¹H-NMR (500 MHz, DMSO) δ 3.86-3.67 (3H, m), 3.25-3.14 (4H, m), 2.84-2.75(4H, m), 0.09 (9H, s).

Preparation Example 2

After a methylene chloride solution, in which 11 g (63.2 mmol) of ethylpiperazine-1-carboxylate was dissolved, was added to a 1 L round-bottomflask, a methylene chloride solution, in which 17.6 ml (126.4 mmol) oftriethylamine and 8.8 ml (69.5 mmol) of trimethylsilyl chloride weredissolved at 0° C., was sequentially added. Thereafter, a reaction wasperformed while stirring for 12 hours at room temperature, the reactionwas terminated, hexane was added to dilute the solution, and the solventwas then removed under reduced pressure. Thereafter, a washing processwas repeated three times using hexane to obtain a modifier representedby the following Formula 1-2. ¹H nuclear magnetic resonancespectroscopic data of the obtained modifier represented by Formula 1-2are as follows.

¹H-NMR (500 MHz, DMSO) δ 4.24-4.01 (2H, m), 3.25-3.14 (4H, m), 2.84-2.75(4H, m), 1.32-1.10 (3H, m), 0.09 (9H, s).

Preparation Example 3

After a methylene chloride solution, in which 12 g (63.2 mmol) of propylpiperazine-1-carboxylate was dissolved, was added to a 1 L round-bottomflask, a methylene chloride solution, in which 17.6 ml (126.4 mmol) oftriethylamine and 8.8 ml (69.5 mmol) of trimethylsilyl chloride weredissolved at 0° C., was sequentially added. Thereafter, a reaction wasperformed while stirring for 12 hours at room temperature, the reactionwas terminated, hexane was added to dilute the solution, and the solventwas then removed under reduced pressure. Thereafter, a washing processwas repeated three times using hexane to obtain a modifier representedby the following Formula 1-3. ¹H nuclear magnetic resonancespectroscopic data of the obtained modifier represented by Formula 1-3are as follows.

¹H-NMR (500 MHz, DMSO) δ 4.24-4.01 (2H, m), 3.25-3.14 (4H, m), 2.84-2.75(4H, m), 1.83-1.64 (2H, m), 1.12-0.93 (3H, m), 0.09 (9H, s).

Preparation Example 4

After a methylene chloride solution, in which 13 g (63.2 mmol) of butylpiperazine-1-carboxylate was dissolved, was added to a 1 L round-bottomflask, a methylene chloride solution, in which 17.6 ml (126.4 mmol) oftriethylamine and 8.8 ml (69.5 mmol) of trimethylsilyl chloride weredissolved at 0° C., was sequentially added. Thereafter, a reaction wasperformed while stirring for 12 hours at room temperature, the reactionwas terminated, hexane was added to dilute the solution, and the solventwas then removed under reduced pressure. Thereafter, a washing processwas repeated three times using hexane to obtain a modifier representedby the following Formula 1-4. ¹H nuclear magnetic resonancespectroscopic data of the obtained modifier represented by Formula 1-4are as follows.

¹H-NMR (500 MHz, DMSO) δ 4.01-3.79 (2H, m), 3.25-3.14 (4H, m), 2.84-2.75(4H, m), 1.56-1.38 (2H, m), 1.38-1.16 (2H, m), 1.00-0.81 (3H, m), 0.09(9H, s).

Preparation Example 5

After a methylene chloride solution, in which 14 g (63.2 mmol) of pentylpiperazine-1-carboxylate was dissolved, was added to a 1 L round-bottomflask, a methylene chloride solution, in which 17.6 ml (126.4 mmol) oftriethylamine and 8.8 ml (69.5 mmol) of trimethylsilyl chloride weredissolved at 0° C., was sequentially added. Thereafter, a reaction wasperformed while stirring for 12 hours at room temperature, the reactionwas terminated, hexane was added to dilute the solution, and the solventwas then removed under reduced pressure. Thereafter, a washing processwas repeated three times using hexane to obtain a modifier representedby the following Formula 1-5. ¹H nuclear magnetic resonancespectroscopic data of the obtained modifier represented by Formula 1-5are as follows.

¹H-NMR (500 MHz, DMSO) δ 4.02-3.82 (2H, m), 3.25-3.14 (4H, m), 2.84-2.75(4H, m), 1.71-1.50 (2H, m), 1.48-1.29 (4H, m), 1.00-0.81 (3H, m), 0.09(9H, s).

Comparative Preparation Example 1

After a methylene chloride solution, in which 11 g (63.2 mmol) of methyl2-(piperazin-1-yl)acetate was dissolved, was added to a 1 L round-bottomflask, a methylene chloride solution, in which 17.6 ml (126.4 mmol) oftriethylamine and 8.8 ml (69.5 mmol) of trimethylsilyl chloride weredissolved at 0° C., was sequentially added. Thereafter, a reaction wasperformed while stirring for 12 hours at room temperature, the reactionwas terminated, hexane was added to dilute the solution, and the solventwas then removed under reduced pressure. Thereafter, a washing processwas repeated three times using hexane to obtain a modifier representedby the following Formula i. ¹H nuclear magnetic resonance spectroscopicdata of the obtained modifier represented by Formula i are as follows.

¹H-NMR (500 MHz, DMSO) δ 3.75-3.58 (3H, s), 3.45-3.24 (2H, m), 2.84-2.75(4H, m), 2.44-2.22 (4H, m), 0.09 (9H, s).

Comparative Preparation Example 2

After a methylene chloride solution, in which 10 g (63.2 mmol) of methylpiperazine-1-carboxylate was dissolved, was added to a 1 L round-bottomflask, a methylene chloride solution, in which 17.6 ml (126.4 mmol) oftriethylamine and ml (69.5 mmol) of (chloromethyl)trimethylsilane weredissolved at 0° C., was sequentially added. Thereafter, a reaction wasperformed while stirring for 12 hours at room temperature, the reactionwas terminated, hexane was added to dilute the solution, and the solventwas then removed under reduced pressure. Thereafter, a washing processwas repeated three times using hexane to obtain a modifier representedby the following Formula ii. ¹H nuclear magnetic resonance spectroscopicdata of the obtained modifier represented by Formula ii are as follows.

¹H-NMR (500 MHz, DMSO) δ 3.87-3.68 (3H, s), 3.30-3.11 (4H, m), 2.58-2.37(4H, m), 1.80-1.59 (2H, s), 0.31-0.13 (9H, s).

Example 1

900 g of 1,3-butadiene and 6.6 kg of n-hexane were added to a 20 Lautoclave reactor, and an internal temperature of the reactor was thenincreased to 70° C. After a catalyst composition, which was prepared bya reaction of a hexane solution having 0.10 mmol of a neodymium compound(NdV, neodymium versatate) with 0.89 mmol of diisobutylaluminum hydride(DIBAH), 0.24 mmol of diethylaluminum chloride, and 3.3 mmol of1,3-butadiene, was added to the reactor, polymerization was performedfor 60 minutes. Thereafter, a hexane solution including 0.23 mmol of themodifier represented by Formula 1-1, which was prepared in PreparationExample 1, was added, and a modification reaction was then performed at70° C. for 30 minutes. Thereafter, a hexane solution, in which 1.0 g ofa polymerization terminator was included, and 33 g of a solution, inwhich 30 wt % of WINGSTAY (Eliokem SAS, France), as an antioxidant, wasdissolved in hexane, were added. A polymer thus obtained was put in hotwater heated by steam and stirred to remove the solvent, and was thenroll-dried to remove the remaining solvent and water to prepare amodified butadiene polymer.

Example 2

A modified butadiene polymer was prepared in the same manner as inExample 1 except that a modification reaction was performed by using themodifier represented by Formula 1-2, which was prepared in Example 2,instead of the modifier represented by Formula 1-1 which was prepared inPreparation Example 1, in Example 1.

Example 3

A modified butadiene polymer was prepared in the same manner as inExample 1 except that a modification reaction was performed by using themodifier represented by Formula 1-3, which was prepared in Example 3,instead of the modifier represented by Formula 1-1 which was prepared inPreparation Example 1, in Example 1.

Example 4

A modified butadiene polymer was prepared in the same manner as inExample 1 except that a modification reaction was performed by using themodifier represented by Formula 1-4, which was prepared in Example 4,instead of the modifier represented by Formula 1-1 which was prepared inPreparation Example 1, in Example 1.

Example 5

A modified butadiene polymer was prepared in the same manner as inExample 1 except that a modification reaction was performed by using themodifier represented by Formula 1-5, which was prepared in Example 5,instead of the modifier represented by Formula 1-1 which was prepared inPreparation Example 1, in Example 1.

Comparative Example 1

900 g of 1,3-butadiene and 6.6 kg of n-hexane were added to a 20 Lautoclave reactor, and an internal temperature of the reactor was thenincreased to 70° C. After a catalyst composition, which was prepared bya reaction of a hexane solution having 0.10 mmol of a neodymium compound(NdV) with 0.89 mmol of diisobutylaluminum hydride (DIBAH), 0.24 mmol ofdiethylaluminum chloride, and 3.3 mmol of 1,3-butadiene, was added tothe reactor, polymerization was performed for 60 minutes. Thereafter, ahexane solution, in which 1.0 g of a polymerization terminator wasincluded, and 33 g of a solution, in which 30 wt % of WINGSTAY (EliokemSAS, France), as an antioxidant, was dissolved in hexane, were added. Apolymer thus obtained was put in hot water heated by steam and stirredto remove the solvent, and was then roll-dried to remove the remainingsolvent and water to prepare a butadiene polymer.

Comparative Example 2

BR1208 (SEETEC) was used as an unmodified butadiene polymer inComparative Example.

Comparative Example 3

CB25 (Lanxess) was used as an unmodified butadiene polymer inComparative Example.

Comparative Example 4

A modified butadiene polymer was prepared in the same manner as inExample 1 except that a modification reaction was performed by using themodifier represented by Formula i, which was prepared in ComparativeExample 1, instead of the modifier represented by Formula 1-1 which wasprepared in Preparation Example 1, in Example 1.

Comparative Example 5

A modified butadiene polymer was prepared in the same manner as inExample 1 except that a modification reaction was performed by using themodifier represented by Formula ii, which was prepared in ComparativeExample 2, instead of the modifier represented by Formula 1-1 which wasprepared in Preparation Example 1, in Example 1.

Experimental Example 1

Physical properties of each of the modified or unmodified butadienepolymers prepared in Examples 1 to 5 and Comparative Examples 1 to 5were respectively measured by the following methods, and the resultsthereof are presented in Table 1 below.

1) Weight-average Molecular Weight (Mw), Number-average Molecular Weight(Mn), and Molecular Weight Distribution

Each polymer was dissolved in tetrahydrofuran (THF) at 40° C. for 30minutes, and then loaded and flowed into a gel permeation chromatography(GPC) column. In this case, as the column, two PLgel Olexis (productname) columns by Polymer Laboratories and one PLgel mixed-C (productname) column by Polymer Laboratories were combined and used. Also, allnewly replaced columns were mixed-bed type columns, and polystyrene wasused as a GPC standard material.

2) Mooney Viscosity and −S/R Value

Mooney viscosity (MV) of each polymer was measured with a large rotor ata rotor speed of 2±0.02 rpm at 100° C. using MV2000E by MonsantoCompany. After each polymer was left standing for 30 minutes or more atroom temperature (23±3° C.), 27±3 g of each polymer was taken as asample used in this case and filled into a die cavity, and Mooneyviscosity was measured while applying a torque by operating a platen.

Also, a change in the Mooney viscosity obtained while the torque wasreleased during the measurement of the Mooney viscosity was observed for1 minute, and a −S/R value was determined from its slope.

3) Structural Analysis

Fourier transform infrared spectroscopy was performed on each polymer,and cis-1,4 bond content, trans-1,4 bond content, and vinyl content ineach polymer were calculated from the result thereof.

4) Solution Viscosity (MU): After a toluene polymer solution includingeach polymer in an amount of 5 wt % was prepared, viscosity of eachsolution was measured at 20° C.

TABLE 1 Example Comparative Example Category 1 2 3 4 5 1 2 3 4 5 Whetheror not Modified Unmodified Modified modified GPC Mn (×10⁵ g/mol) 2.302.43 2.38 2.40 2.21 2.72 1.57 2.64 2.47 2.44 results Mw(×10⁵ g/mol) 6.126.46 6.21 6.41 6.08 7.30 7.78 6.18 6.70 6.78 Mw/Mn 2.66 2.74 2.61 2.672.75 2.68 4.96 2.35 2.71 2.78 MV(ML1+4, @100° C.) 43 46 44 46 42 42 4545 47 46 (MV) -S/R 0.7456 0.7523 0.7441 0.743 0.7371 0.698 0.7274 0.65850.7018 0.7123 Solution 216.0 218.0 208.0 218.0 204.0 207.0 242 146 224.0220.0 viscosity (MU) Structural Cis-1,4 97.5 97.8 97.3 97.2 97.4 97.896.2 96.6 97.1 96.8 analysis bond Vinyl 0.5 0.5 0.7 0.8 0.6 0.8 2.0 0.50.7 0.6 Trans- 2.0 1.8 2.0 2.0 2.0 1.4 1.8 2.9 2.2 2.6 1,4 bond

As illustrated in Table 1, it was confirmed that the modified butadienepolymers of Examples 1 to 5, which were prepared by using an exemplarymodifier of the modifier represented by Formula 1 according to theembodiment of the present invention, had −S/R values which wereincreased in comparison to the unmodified butadiene polymers ofComparative Examples 1 to 3 and the modified butadiene polymers ofComparative Examples 4 and 5. This denoted that the modified butadienepolymers according to the embodiment of the present invention had higherlinearity than the modified or unmodified butadiene polymers ofComparative Examples 1 to 5, and, as a result, this indicated thatresistance characteristics and fuel economy of rubber samples, whichwere prepared from rubber compositions including the same, may beexcellent.

Experimental Example 2

After rubber compositions and rubber samples were prepared by using themodified or unmodified butadiene polymers of Examples 1 to 5 andComparative Examples 1 to 5, tensile strength, 300% modulus, elongation,abrasion resistance, and viscoelasticity were respectively measured bythe following methods. The results thereof are presented in Table 2below, and each measured value was expressed by indexing measurementvalues of Comparative Example 1 at 100.

Specifically, with respect to the rubber compositions, 70 parts byweight of carbon black, 22.5 parts by weight of process oil, 2 parts byweight of antioxidant (TMDQ), 3 parts by weight of zinc oxide (ZnO), and2 parts by weight of stearic acid were mixed with 100 parts by weight ofeach of the modified butadiene polymers and the butadiene polymers toprepare each rubber composition. Thereafter, 2 parts by weight ofsulfur, 2 parts by weight of a vulcanization accelerator (CZ), and 0.5part by weight of a vulcanization accelerator (DPG) were added to eachrubber composition, and vulcanization was performed at 160° C. for 25minutes to prepare each rubber sample.

1) Tensile Strength (kg·f/cm²), 300% Modulus (kg·f/cm²), and Elongation(%)

After the vulcanization of each rubber composition at 150° C. for 90minutes, tensile strength of each vulcanizate, a modulus at 300%elongation (M-300%), and an elongation of each vulcanizate at break weremeasured according to ASTM D412.

2) Viscoelasticity (Tan δ @60° C.)

With respect to Tan δ property that is most important for low fuelconsumption property, a viscoelastic coefficient (Tan δ) was measured ata frequency of 10 Hz, a prestrain of 5%, a dynamic strain of 3%, and atemperature of 60° C. using DMTS 500N by Gabo Instruments, Germany. Inthis case, the lower the Tan δ at 60° C. was, the lower the hysteresisloss was and the better the low rotation resistance, i.e., fuel economywas.

3) DIN Abrasion Test

A DIN abrasion test was performed on each rubber sample according toASTM D5963 to obtain DIN wt loss index (Loss Volume Index: ARIA(Abrasion resistance index, Method A). The higher the index was, thebetter the abrasion resistance was.

TABLE 2 Example Comparative Example Category 1 2 3 4 5 1 2 3 4 5 DIN wtloss 108 107 108 108 106 100 89 103 99 98 Index Tensile M-300% 109 108108 106 107 100 95 103 101 102 properties (Index) Tensile 106 105 105104 104 100 96 102 100 101 strength (Index) Elongation 95 97 96 95 96100 101 98 98 99 (Index) Tan δ @60° C. 108 109 108 107 107 100 95 102102 103 (Index)

As illustrated in Table 2, it was confirmed that the rubber compositionsincluding the modified butadiene polymers of Examples 1 to 5 prepared byusing the modifiers according to the embodiment of the present inventionand the rubber samples prepared therefrom had significantly improvedviscoelastic properties (the index was significantly increased bydecreasing the Tan δ at 60° C.) while having improved abrasionresistances and tensile properties in comparison to the rubbercompositions respectively including the unmodified butadiene polymers ofComparative Examples 1 to 3 and the modified butadiene polymers ofComparative Examples 4 and 5 and the rubber samples prepared therefrom.

Specifically, with respect to the butadiene polymer of ComparativeExample 1, which was prepared under the same conditions as the modifiedbutadiene polymers of Examples 1 to 5 except that a modificationreaction was not performed by using a modifier, and the commerciallyavailable butadiene polymers of Comparative Examples 2 and 3, tensileproperties similar to those of the modified butadiene polymers ofExamples 1 to 5 were obtained, but abrasion resistances weresignificantly decreased and viscoelastic properties were significantlyreduced.

Also, the modified butadiene polymers of Examples 1 to 5 had improvedviscoelastic properties while having better abrasion resistances andtensile properties than the modified butadiene polymers of ComparativeExamples 4 and 5 which were respectively prepared by modification withthe materials which included an alkoxysilane group, an amine group, andan ester group as the modifier represented by Formula 1 according to theembodiment of the present invention, but had a different structure.

The results indicated that, since the modified butadiene polymers of theexamples according to the embodiment of the present invention weremodified with the specific modifier represented by Formula 1, themodified butadiene polymers of the present invention may have excellentlow rotation resistance, i.e., fuel efficiency, while having tensileproperties and abrasion resistances equal to or better than those of theunmodified butadiene polymers or the butadiene polymers modified withthe similar but different structured modifiers.

1. A modifier represented by Formula 1:

wherein, in Formula 1, R₁, R₂, and R₅ are each independently amonovalent hydrocarbon group having 1 to 20 carbon atoms which issubstituted or unsubstituted with at least one substituent selected fromthe group consisting of an alkyl group having 1 to 20 carbon atoms, acycloalkyl group having 3 to 20 carbon atoms, and an aryl group having 6to 30 carbon atoms, R₃ and R₄ are each independently a divalenthydrocarbon group having 1 to 20 carbon atoms which is substituted orunsubstituted with an alkyl group having 1 to 20 carbon atoms, and n isan integer of 1 to
 3. 2. The modifier of claim 1, wherein, in Formula 1,R₁, R₂, and R₅ are each independently an alkyl group having 1 to 10carbon atoms which is substituted or unsubstituted with an alkyl grouphaving 1 to 10 carbon atoms, and R₃ and R₄ are each independently analkylene group having 1 to 6 carbon atoms.
 3. The modifier of claim 1,wherein the modifier represented by Formula 1 is represented by Formulae1-1 to 1-5:


4. The modifier of claim 1, wherein the modifier is a modifier for aconjugated diene-based polymer.
 5. A modified conjugated diene-basedpolymer comprising a functional group derived from a modifierrepresented by Formula 1:

wherein, in Formula 1, R₁, R₂, and R₅ are each independently amonovalent hydrocarbon group having 1 to 20 carbon atoms which issubstituted or unsubstituted with at least one substituent selected fromthe group consisting of an alkyl group having 1 to 20 carbon atoms, acycloalkyl group having 3 to 20 carbon atoms, and an aryl group having 6to 30 carbon atoms, R₃ and R₄ are each independently a divalenthydrocarbon group having 1 to 20 carbon atoms which is substituted orunsubstituted with an alkyl group having 1 to 20 carbon atoms, and n isan integer of 1 to
 3. 6. The modified conjugated diene-based polymer ofclaim 5, wherein the modifier represented by Formula 1 is represented byFormulae 1-1 to 1-5:


7. The modified conjugated diene-based polymer of claim 5, wherein thepolymer has a number-average molecular weight of 100,000 g/mol to500,000 g/mol.
 8. The modified conjugated diene-based polymer of claim5, wherein the polymer has a molecular weight distribution (Mw/Mn) of2.0 to 3.0.
 9. The modified conjugated diene-based polymer of claim 8,wherein the polymer has a −S/R (stress/relaxation) value at 100° C. of0.7 or more.
 10. A method of preparing the modified conjugateddiene-based polymer of claim 5, the method comprising: (1) preparing anactive polymer coupled with an organometal by polymerization of aconjugated diene-based monomer in a hydrocarbon solvent in the presenceof a catalyst composition including a lanthanide rare earthelement-containing compound; and (2) reacting the active polymer with amodifier represented by Formula 1:

wherein, in Formula 1, R₁, R₂, and R₅ are each independently amonovalent hydrocarbon group having 1 to 20 carbon atoms which issubstituted or unsubstituted with at least one substituent selected fromthe group consisting of an alkyl group having 1 to 20 carbon atoms, acycloalkyl group having 3 to 20 carbon atoms, and an aryl group having 6to 30 carbon atoms, R₃ and R₄ are each independently a divalenthydrocarbon group having 1 to 20 carbon atoms which is substituted orunsubstituted with a linear or branched alkyl group having 1 to 20carbon atoms, and n is an integer of 1 to
 3. 11. The method of claim 10,wherein the catalyst composition is used in an amount such that thelanthanide rare earth element-containing compound is included in anamount of 0.1 mmol to 0.5 mmol based on 100 g of the conjugateddiene-based monomer.
 12. The method of claim 11, wherein the lanthaniderare earth element-containing compound comprises a neodymium-basedcompound represented by Formula 3:

wherein, in Formula 3, R_(a) to R_(c) are each independently hydrogen oran alkyl group having 1 to 12 carbon atoms, but all of R_(a) to R_(c)are not hydrogen at the same time.
 13. The method of claim 12, whereinthe neodymium-based compound comprises at least one selected from thegroup consisting of Nd(2,2-diethyl decanoate)₃, Nd(2,2-dipropyldecanoate)₃, Nd(2,2-dibutyl decanoate)₃, Nd(2,2-dihexyl decanoate)₃,Nd(2,2-dioctyl decanoate)₃, Nd(2-ethyl-2-propyl decanoate)₃,Nd(2-ethyl-2 butyl decanoate)₃, Nd(2-ethyl-2-hexyl decanoate)₃,Nd(2-propyl-2-butyl decanoate)₃, Nd(2-propyl-2-hexyl decanoate)₃,Nd(2-propyl-2-isopropyl decanoate)₃, Nd(2-butyl-2-hexyl decanoate)₃,Nd(2-hexyl-2-octyl decanoate)₃, Nd(2,2-diethyl octanoate)₃,Nd(2,2-dipropyl octanoate)₃, Nd(2,2-dibutyl octanoate)₃, Nd(2,2-dihexyloctanoate)₃, Nd(2-ethyl-2-propyl octanoate)₃, Nd(2-ethyl-2-hexyloctanoate)₃, Nd(2,2-diethyl nonanoate)₃, Nd(2,2-dipropyl nonanoate)₃,Nd(2,2-dibutyl nonanoate)₃, Nd(2,2-dihexyl nonanoate)₃,Nd(2-ethyl-2-propyl nonanoate)₃, and Nd(2-ethyl-2-hexyl nonanoate)₃. 14.The method of claim 10, wherein the modifier is used in an amount of 0.5mol to 20 mol based on 1 mol of the lanthanide rare earthelement-containing compound.